1. Field of the Invention
The invention relates to an arrangement for controlling the electrode height in an arc furnace fed from a transformer. In particular, the invention relates to an arrangement in which an impedance controller controls the height of the electrode or, in 3-phase arc furnaces, of each of the electrodes above the material being melted in response to an impedance signal obtained from one measuring element furnishing a quantity proportional to the electrode voltage measured between the secondary terminal of the transformer of the respective electrode and the furnace jacket, and another measuring element furnishing a quantity proportional to the electrode current of the same electrode.
2. The Prior Art
In known arrangements of this kind shown in German Auslegeschrift No. 1,183,185 and German Auslegeschrift No. 1,163,996, a control deviation for the impedance is obtained directly from the measured quantities proportional to the electrode voltage between the transformer terminal and the furnace jacket, and the electrode current.
It is known in addition, as shown in U.S. Pat. No. 2,367,979 and German Auslegeschrift No. 2,238,006, to vary the desired impedance value as a function of the supply voltage of the arc furnace by means of a function generator influencing the quantity proportional to the electrode voltage.
Strictly speaking, the known arrangement according to German Auslegeschrift No. 2,238,006, supra, operates in principle not with impedance control but with a linearized admittance control.